Mail signatures duplicated when I change accounts

When I open Mail I have new messages sending out from Account1 by default, using the Account1 signature. When I switch to have the email sent from Account2, it's showing the Account2 signature underneath the Account1 signature. So I have to go in and delete Account1 signature every time. How can I get rid of this without having to do it manually every time?

I have it set like that so each account has its own signature, but for some reason when I open a new message with Account1, it shows Account1's signature. But if I change the email to be sent from Account2, it keeps Account1's signature and adds that of Account2. What I want to know is why it keeps the old signature if I'm switching mail accounts.

Ok. I'm toggling between accounts with a new mail in Mavericks and it's changing the signature fine.
In the open mail, when you change the 'From' account what happens in the 'Signature' tab opposite right?

Edit. Check how each default signature is written. You may have inadvertently pasted one above the other.